The invention relates to a method for sorting rolls of paper and paperboard web into a desired order ready for shipping according to customer orders.
The invention also relates to an assembly suitable for implementing the method.
In mills producing paper and paperboard, rolls ordered by customers are slit and wound to a desired width from a large machine roll at a slitter-winder. The customer rolls are slit from the machine roll so as to minimize the amount of waste. Inasmuch a given customer order cannot be fulfilled in all cases by slitting a single machine roll or the customer order may specify roll widths that cannot be slit in an evenly divisional manner from a roll, it is frequently necessary to slit a machine roll so that the slit rolls belong to different shipments. Hence, the slit rolls must be sorted latest before the rolls are to be delivered according to customer orders to their appropriate shipment lots. Such a need for sorting and regrouping of rolls arises due to, e.g., different roll sizes, shipping routes and customers. The sorting system must have a sufficient capacity and extensibility to cope with variations in customer orders and changes in grades produced. The system must be able to handle flexibly and rapidly all produced rolls inasmuch the manufacture runs continuously and the mill cannot be designed to have a large intermediate storage to buffer all the capacity of the different production steps at a mill. Furthermore, the system must offer gentle handling of the rolls to avoid causing damage thereto, and bulk shipping systems of rolls have to offer fast storage and unloading of a desired set of rolls. Typically, the footprint allocated for roll handling systems is very limited in a mill. The space available in existing buildings is predetermined, and the cost of a cubic meter unit volume in new buildings dictates the feasible size of the building and, thus, the available space.
Conventionally, the papermaking industry has accomplished the handling of rolls generally by means of sorting ramps and different kinds of high-bay rack storage systems, normally of the automated kind. Of these systems, high-bay racks offer the largest capacity. The sorting ramp comprises a slanted surface along which rolls are rolled downward. Flush with the surface of the ramp are adapted stops, generally in plural rows. The stops can be elevated up from the ramp at desired points, whereby a roll that is rolling toward the stop can be halted at a desired point. Conventionally, the lower end of the ramp terminates at a conveyor that takes the sorted rolls forward in the system. Sorting takes place so that, e.g., a set of rolls received from a slitter-winder is pushed to roll downward along the ramp and rolls belonging to a given shipment are halted by the stops. Arranging the stops in plural rows gives the possibility of dividing rolls slit from a single machine roll into several groups and, further, of combining rolls slit from different machine rolls with rolls slit from other machine rolls. After halting onto the slanted surface of the ramp all the rolls belonging to a given shipment, the rolls can be released, whereby they roll down onto the conveyor located at the lower end of the ramp. Usually, a ramp type sorting system is used for collecting rolls into groups to be transferred by a lift truck to packaging or, possibly, for altering the mutual order of rolls during or prior to their packaging. Ramp systems have also been used for collecting rolls into trailer loads, but herein some capacity problems have been encountered. The capacity of a ramp system is dependent on the number of ramps, and the largest systems can accommodate 200 to 250 rolls at a time. In addition to its limited capacity, a ramp system has been hampered by the risk of damage to the rolls from their rolling and stopping, not to mention the need for a large footprint
Rack storages are used for combining trailer loads, as intermediate storages and as shipping storages. They are characterized by a large handling and storage capacity, as well as good flexibility. Rack storages fall in two major categories, wherein one type of rack storage provides an individual shelf for each roll, while the other type of rack storage has the rolls stored in groups that are stored horizontally along a store lane. The type of rack storage having one shelf reserved for each roll offers a maximized flexibility inasmuch each roll can be picked up individually from the storage.
On the other hand, efficient management of the storage needs fast roll-handling equipment and multiple infeed/fetch systems of rolls thus making the cost of the great capacity and flexibility high, whereby the use of this kind of storage is justified only when a relatively high capacity is requested. The average count of rolls in a storage designed for handling rolls individually may be 3000 rolls, while the infeed capacity is about 160 rolls/h and the fetch capacity about 240 rolls/h. If the rolls are grouped in the storage tightly against each other, the footprint of the storage may be reduced with the penalty of losing the possibility of individual roll handling.
It is an object of the present invention to provide a sorting/storage system featuring a capacity greater than that of a ramp system, a handling technique of rolls with a minimized risk of damage to rolls and a small footprint.
The goal of the invention is achieved by way of sorting incoming rolls with the help of an infeed conveyor onto at least two receiving conveyors into a desired order, whereupon during the transfer of the rolls to the receiving conveyor, the rolls thus sorted into the desired order are grouped into an end-to-end abutting batch with each other. After each receiving conveyor has become full so that it contains a fill number of rolls forming a predetermined unit load for an upender lift, the rolls can be unloaded from the receiving conveyor as unit loads of the upender lift.
According to an embodiment of the invention, after the receiving conveyor is full of rolls, all the rolls resting on the conveyor are transferred as an end-to-end abutting group onto a storage conveyor that is placed as an extension of the receiving conveyor.
According to another embodiment of the invention, the number of parallel-operating infeed and receiving conveyors is three of each and two or more conveyor groups are arranged to operate above one another.
The invention offers significant benefits.
The system comprises standard equipment, which makes its design, construction and even retrofitting easy to implement. The rolls are handled only in their longitudinal direction by moving them on conveyors thus avoiding the risk of damage to the rolls that may occur from their rotational movement and bumps during roll transfer. The system is extremely compact and can be fitted on a footprint smaller than that required by a ramp system of equivalent roll handling capacity. Furthermore, the system makes it possible to utilize the storage space also in the vertical dimension, whereby the storage capacity per square meter of the building floor area is maximized. The system capacity is higher than that achievable in a ramp system and it is readily controllable. If the system is required to provide a large storage capacity, it can be complemented with a required number of conveyors acting as buffer storage means.